Process of preparing 2-phenylethanol-1



United States Patent PROCESS OF PREPARING Z-PHENYLETHANOL-l Muus Gerrit Jan Beets, Hilversum, Netherlands, and

Emanuel Alexander Drukker, Milwaukee, Wis., assignors to N. V. Polak & Schwarzs Essencefabrieken, Hilversum, Netherlands, a corporation of the Netherlands No Drawing. Application March 23, 1954 Serial No. 418,217

Claims priority, application Netherlands December 14, 1950 6 Claims. (Cl. 260-618) The present invention relates to a novel and improved process of preparing 2-phenylethanol-1.

This is a continuation-in-part of our application Serial No. 259,881, filed December 4, 1951, and now abandoned.

Phenylethyl alcohol (2-phenylethanol-1) may be considered one of the most important raw materials in the perfume industry.

Numerous methods of preparing this compound have been described in the literature.

Esters of phenyl acetic acid can be reduced to phenylethyl alcohol with sodium and alcohol, according to L. Bouveault and C. Blanc, Compt. Rend. 137, 60 (1903), or, according to U. S. Patent No. 2,091,800, with the aid of'copper chromium oxide catalysts.

Condensation of benzene with ethylene oxide under the action of aluminum chloride also leads to the formation of phenylethyl alcohol (U. S. Patents Nos. 1,944,959 and 2,013,710) just as the condensation of alkaliphenyl (German Patent No. 596,523) or phenylmagnesium bromide (U. S. Patent No. 1,996,746; German Patents Nos. 660,075 and 697,420) with ethylene oxide or ethylenechlorohydrin.

fi-Phenylethyl alcohol can also be prepared by chlorination of ethylbenzene followed by selective hydrolysis, according to :U. :8. Patent No. 2,185,141, or by hydrogenation of phenylacetaldehyde (Ber. 56, 2176 (1923)).

These methods of preparation, however, all have certain disadvantages. Some start from complex raw materials or require the use of expensive auxiliary substances or reaction conditions, such as reduction of esters with sodium and alcohol, reduction of phenylacetaldehyde (method of Grignard); others proceed in a large dilution or give impure final products which render a particular purification process necessary (reaction of Friedel- Crafts).

In this respect, U. S. Patent No. 2,524,096, according to which the catalytic reduction of styrene oxide gives a good yield of fl-phenylethyl alcohol, constitutes an improvement over the prior art.

We have now found that it is not necessary to start from styrene oxide, a raw material which is prepared in a very inefiicient manner from styrene with the aid of peroxides or from l-phenyl 2-halogenethanol-l, but that 1-phenyl-2-halogen-ethanol-l can be catalytically reduced directly to fl-phenylethyl alcohol, provided that the reduction is carried out in the presence of a compound able to combine hydrogen halide acid. Preferably strong alkalis are used for this purpose. The reaction is eiiected under the influence of a low temperature hydrogenation catalyst. Raney nickel, palladium oxide and platinum on carbon have been found to be elfective for this purpose.

With this method, styrene oxide is first formed from styrene halogenhydrin in the aggregate in which the reaction takes place, whereupon immediate reduction to fl-phenylethanol follows.

It is surprising that this reaction gives an excellent yield, which is higher than the yield obtained when working via purified styrene oxide, while proceeding without the formation of undesirable by-products, considering that two competing reactions are possible under these circumstances, to wit:

n Pa-on on. rh-on,cn.on

in which Ph represents phenyl and X halogen.

It is remarkable that Reaction 1 does not occur at all here since the halogen atom can be considered as one of the groups which is most easily hydrogenolized.

The above-described process has considerable technical advantages. Since styrene oxide, as already mentioned, can be efficiently prepared only from styrene halogenhydrin, it is an advantage that, according to the present invention, this conversion is not necessary as a separate treatment.

A considerable advantage is also that the halogenhydrin can be treated in an entirely crude form because styrene halogenhydrin can be most simply prepared in aqueous medium. Dihalostyrene is generally obtained as a by-product or impurity. The mixture of the reac tion products has a high density and immediately separates as an oil from the reaction medium after completion of the treatment, whereupon it can be separated easily from the aqueous upper layer.

According to the present invention, this crude reaction product need not be purified in any way since the byproduct present is converted under our reaction conditions into the volatile ethylbenzene which, consequently, can be easily removed by fractional distillation. Conversion of thecrude styrene halogenhydrin-containing reaction mixture into B-phenylethyl alcohol is now possible without any loss of yield or reduction of the quality of the final product.

This final product only needs to be purified by a simple distillation to be obtained in a completely pure form.

Neither the odor nor the chemical purity of the B- phenyl-ethanol obtained from either purified or crude styrene halogen-hydrin differ from the product prepared from pure styrene oxide.

Styrene halogenhydrins may be prepared, e. g. according to A. Detoeuf (Bull. (4) 31 (1922), 169) by reacting styrene with an aqueous solution of chlorourea or, according to U. S. Patent No. 2,237,284, by reacting styrene with halogen and water.

The following examples are given to illustrate the invention which, however, is not limited to these specific embodiments.

Example I 91 g. (0.58 mol) of styrene chlorohydrin, 78 g. (0.64 mol) of 33% caustic soda,. and 50 g. of water, together with a small quantity of Raney-nickel, were introduced in a stainless steel shaking autoclave. The hydrogenation was carried out at room temperature and a maximal hydrogen pressure of 25 atmospheres. The catalyst was removed, and the oil layer separated and distilled after washing in vacuo.

Yield: 58 g. of fl-phenylethyl alcohol or 81.5% of theoretical. Boiling point: 84/4 mm. n 1.5320.

Example II 402 g. (2 mols) of styrenebromohydrin, 267 g. (2.2

Example III 100.5 g. (0.5 mol) of styrenebromohydrin and 230 g. of a 40% aqueous solution of trimethylbenzylammoniumhydroxide were brought into an autoclave together with a small quantity of Raney-nickel. The hydrogenation was carried out at room temperature and a maximum pressure of 25 atmospheres and was completed in approximately 3 hours. The'yield amounted to 33 g. of ,B-phenylethanol or 54% of theoretical.

Example IV 940 g. of a crude mixture mainly consisting of styrenebromohydrin and approximately 24% of dibromostyrene, and 625 g. of 33% caustic soda were brought into an autoclave together with a small quantity of Raney-nickel. The reduction proceeded as in Example III and yielded 368 g. of B-phenylethyl alcohol. n 1.5323. Soluble in 12.2 volumes of 30% ethanol.

Example V 402 g. of styrenebromohydrin, 430 g. of bariumhy droxide hydrate, 300 cm. of water and a small quantity of Raney-nickel were brought into an autoclave. The reaction proceeded as in Example III and resulted in a yield of 180.5 g. of p-phenylethanol or 74% of theoretical. 11 1.5330. Boiling point 82/3 mm.

Example VI 101 g. (0.5 mol) of styrene bromohydrin and a solution of 24 g. (0.6 mol) of sodium hydroxide in 150 g. of water were brought into an autoclave with 1 g. of palladium oxide. The hydrogenation was carried out at room temperature and a pressure of 25 atmospheres. The catalyst was removed, and the oil layer separated and washed. The reaction product was fractionated in vacuo.

Yield: 43 g. of phenylethyl alcohol or 70.5% of theoretical. 41 1.5330. Boiling point at mm. 89-92.

Example VII 101 g. (0.5 mol) of styrene bromohydrin, a solution of 24 g. (0.6 mol) sodium hydroxide in 150 g.v of water and 17.5 g. of a platinum on carbon catalyst (56%) were brought into an autoclave. The hydrogenation was carried out at room temperature and at a pressure of 25 atmospheres. After completion of the hydrogenation,

the reaction product was worked up as described in Example VI and fractionated in vacuo.

Yield: 42 g. of phenylethylalcohol or 69% of theoretical. 11 15328-15334.

What we claim is:

1. The process of preparing 2-phenylethanol-1, comprising treating styrene halogenhydrin, the halogen being selected from the group consisting of chlorine and bromine, at a hydrogen pressure sufiicient to maintain hydrogen in the liquid phase with hydrogen under the influence of a catalyst selected from the group consisting of Raney nickel, palladium oxide and platinum on carbon, and in the presence of an aqueous strongly alkaline reacting substance in an amount at least stoichiometrically equivalent to the halogen, without external heating.

2. The process as defined in claim 1, wherein the catalyst is Raney nickel.

3. The process of preparing 2-phenylethanol-1, comprising treating crude styrene halogenhydrin, the halogen being selected from the group consisting of chlorine and bromine, at a hydrogen pressure suflicient to maintain hydrogen in the liquid phase with hydrogen under the influence of a catalyst selected from the group consisting of Raney nickel, palladium oxide and platinum on carbon, and in the presence of an aqueous strongly alkaline reacting substance in an amount at least stoichiometrically equivalent to the halogen, without external heating.

4. The process as defined in claim 3, wherein the catalyst is Raney nickel. I

5. The process of preparing 2-phenylethanol-1, comprising treating styrene halogenhydrin containing dihalogenstyrene as an impurity, the halogen being selected from the group consisting of chlorine and bromine, at a hydrogen pressure sufiicient to maintain hydrogen in the liquid phase with hydrogen under the influence of a catalyst selected from the group consisting of Raney nickel, palladium oxide and platinum on carbon, and in the presence of an aqueous, strongly alkaline reacting substance in an amount at least stoichiometrically equivalent to the halogen, without external heating.

6. The process as defined in claim 5, wherein the catalyst is Raney nickel.

References Cited in the file of this patent UNITED STATES PATENTS 2,582,114 Frisch Jan. 8, 1952 FOREIGN PATENTS 507,501 Belgium Dec. 15, 1951 699,062 Great Britain Oct. 28, 1953 OTHER REFERENCES Newman et al.: Chem. Abst., vol. 44 (1950), column 2911 1 p.). 

1. THE PROCESS OF PREPARING 2-PHENYLETHANOL-1, COMPRISING TREATING STYRENE HALOGENHYDRIN, THE HALOGEN BEING SELECTED FROM THE GROUP CONSISTING OF CHLORINE AND BROMINE, AT A HYDROGEN PRESSURE SUFFICIENT TO MAINTAIN HYDROGEN IN THE LIQUID PHASE WITH HYDROGEN UNDER THE INFLUENCE OF A CATALYST SELECTED FROM THE GROUP CONSISTING OF RANEY NICKEL, PALLADIUM OXIDE AND PLATINUM ON CARBON, AND IN THE PRESENCE OF AN AQUEOUS STRONGLY ALKALINE REACTING SUBSTANCE IN AN AMOUNT AT LEAST STOICHIOMETRICALLY EQUIVALENT TO THE HALOGEN, WITHOUT EXTERNAL HEATING. 